Optimal quantization employing programmable flash analog to digital converters

In this paper, a novel implementation of optimal scalar quantizers using a programmable floating-gate flash analog to digital converter (ADC) is described. The optimal quantization levels for a given signal class are determined according to the Lloyd-Max algorithm. The optimal quantization decision levels are then programmed as the reference voltages for comparators in the floating-gate flash ADC. A test-bench involving the programmable flash ADC and an FPGA interface to a PC is designed. The proposed setup is tested for several signal classes including speech signals and Gaussian random signals. It is demonstrated that significant ADC performance gain, quantified in terms of the signal to noise ratio, may be obtained when optimal scalar quantization is implemented on the floating-gate flash ADC.